Artificial tooth



H. STURM ARTI FICIAL TEETH Sheets-Sheet 2 Filed June 6, 1925 Flam.

Patented Uec. 2, 1924.

PATENT OFFICE.

HANS STURM, 01E RECHENBER-G, CZECHOSLOVAKIA.

ARTIFICIAL TOOTH.

Application led .Tune 6,

To all 'whom t may concern:

Be it known that I, HANS STURM, citizen of Czechoslovakia, residing at 6 Altstadter Platz, Reichenberg, Czechoslovakia, have invented improvements in and Relating to Artificial Teeth, of which the following is a specification.

A distinction has hitherto been drawn between two kinds of artificial teeth, those in which the metal anchoring means is fused into the ceramic'substance itself, and those having a special anchoring means in the form of a back plate, which, when the artificial tooth is being made, must be cemented to the tooth itself. rI he teeth of the first category have .the disadvantage, that the use of fire at a very high temperature for fusing in the anchoring means, which now-a-days chiefiy consists of base metals is accompanied by the danger of hair cracks in -the porcelain, which cannot be detected owing to their being very fine, but cause the artificial tooth to decay very rapidly when in use. fn the second category of artificial teeth mentioned above the cementing of the parts always introduces a certain amount of insecurity owing to the impossibility of controlling the setting of the cement.

In contradistinction to these older categories of artificial teeth, which suffer from the disadvantages referred to, the subject of the application forms an entirely new category, in which all the mechanical work on the framework carrying the tooth can be carried out apart from the tooth itself and the artificial tooth is only mounted on its metal carrier after the carrier has been quite completed and is fixed on it by means of a resiliently engaging snap fastening.

For thus purpose in constructing the artificial tooth according to the application the crown of the tooth, which is provided with a hook-shaped undercut recess, is fixed to the back plate carrying it by means of an angle hook, which snaps into position, the arrangement being such that it is normally impossible for the hook to become released again unintentionally and that only the ydental mechanic can release the connection by proper manipulation, in case any adjustment should be necessary after the whole set of teeth have been put together. rnll/ihilehitherto in, the metalv anchoring 1923. Serial No. 643,732.

means for artiicial teeth, where a hookshaped metal anchor is cemented into the undercut part of the artificial tooth, the cement lying over the shank of the anchor has to take up the entire pressure caused by chewing, which as a rule causes the connection to become loose very soon and causes the tooth to break away from the bridge, this disadvantage is done away with in the present invention as well.

According to the invention the thickened stem of the angle hook completely fills thc opening in the crown, through which it is introduced, so that the stem itself takes up the pressure due to chewing and provides a firm and durable connection, which is independent of the cement, which easily breaks away and gives.

The angle hook for anchoring the crown to the back plate supporting it can be made by punching it out of the back plate itself and bending it over and be provided on its bottom with a simple strengthening wedge. This strengthening wedge may be provided with a back plate at right angles to it, which is inserted into the opening formed by punching out the anchor. By finally soldering on a covering plate, the opening in the back plate actually supporting the tooth can be closed. During the prepara# tory work an auxiliary wedge is introduced through the opening in the actual back plate, which is still uncovered, into the transverse groove in the tooth, this connection by means of a wedge holding the tooth provisionally to the back plate so firmly that the necessary work can be carried out on the back plate conveniently and accurately with the tooth in position, so as to correspond to the shape of the tooth. When the back plate has been completed, the wedge can be readily released and the tooth removed, so that the remaining work can be carried out and the connection to the bridge made. Finally, the auxiliary wedge, which is used as a handle, is bentover and cut so as to form a filling piece for the opening in the back plate and is secured in the correct position to the stem of the angle hook by being soldered to the back plate. Only after all this work has been completed `is it necessary to definitely nx the tooth to the backfplate, so 'that during all thefpreparatory work, more particularly when doing the necessary soldering to the metal parts, the tooth can be in no Way disturbed or damaged. After the parts have been definitely fixed together, it is only possible to release the connection again, if the back plate with the angle wedge and the tooth are carefully unsoldered from the strengthening plate carrying both parts. Only after this has been done can the angle wedge be Withdrawn through the opening in the back plate now laid bare and, by the back plate and the crown of the tooth being slightly displaced in the longitudinal direction, the anchoring hook can be withdrawn from the undercut part in the crown and be lifted completely out of the recess in the crown.

Instead of making the hooked anchoring member by bending from the back plate, it may be made separate and be attached to the plate subsequently and may be supported by a bracket or the like being bent out of the back of the back plate. ln another modification a separate hooked anchoring member may be fixed to the back plate, which is left uncut, and the stem of the hooked anchoring member is reinforced by a metal strip bent round it, the lower end of this reinforcing strip being formed into a bracket resting against the back plate and acting as a support for the stem of the hooked anchoring member with its supporting plate.

Thus in all the constructional forms of the subject of the invention described above it is )ossible to take all the parts apart without damage, but this can only be done by the expert and an inadvertent separation of the parts is rendered absolutely impossible, as the tooth and its supporting frame are firmly connected together even without any cementing by the locking means, which snap into engagement, while during the preparatory part of the manufacture and the fitting together of all the parts, the latter may still be put together and taken apart, as for instance in the constructional form first described during the first part of manufacture and the fine adjustment of the artificial tooth the back plate has not yet been attached and the wedge, which is subsequently bent to an angle, is straight while being used as an auX- iliary wedge, so that it both provides a convenient handle for the tooth when being prepared and a convenient means for releasing the connection and putting the parts together again.

In the accompanying drawings the constructional forms of the invention described above are shown in detail.

Fig. l being a back view of an artificial tooth according to the first constructional form,

Figs. 2 and 3 a vertical and horizontal section respectively on line A-B of Fig. l,

Fig. 4 a perspective view of the corresponding metal back plate with the anchoring angle hook, which is punched from it,

Fig. 5 a vertical section through the back plate and the tooth with the parts fixed together provisionally for the preparatory work,

Fig. G a perspective view of the back plate with a soldered-on cover plate and of the inserted wedge for strengthening the stein together with the bottom plate just before being definitely inserted,

Figs. 7 and 8 vertical sections through the tooth after it has been Vfinally lixed on its metal supporting plate and just before the two parts have been finally united,

Fig. 9 a perspective view of a second constructional, form with a hooked anchoring n'ieans and strengthening wedge projecting from the back plate and a supporting bracket bent out of the plate,

F ig. l0 a rear view of the corresponding artificial tooth, the back plate being removed,

Fig. ll a vertical section through the artificial tooth and its back plate when united,

Fig. 12 a perspective View of a third con structional form of the invention with hooked anchoring means mounted on the haelt plate and a supporting bracket for the said means,

Fig. i3 a perspective view of the metal strip but in various places, which acts as a supporting bracket for the stem of the hooked anchoring means,

Fig. M. a perspective view of the construetional parts shown in Figs. l2 and l?) after they have been united,

Fig. l5 a view from the back of the corresponding artificial tooth,

F 1G to lf) are views corresponding to Figs. l2 to l5 of a fourth constructional form, in which the hooked anchoring means are vertical.

In the first constructional example the tooth l has a transverse recess 2 at the back, which is provided withan upwardly directed undercut part 2l. From the back plate .l (Fig. Lt) a flat anchoring part 5 having a hook-shaped bent-over part G at the end is punched out. Through the opening 7 thus foimed in the back olate t a removable flat wedge S may be inserted. after the tooth V1 has been placed on the anchor. as shown in Fig. 5, for tenipm'arily clamping the tooth immovably on the anchor 5. (l. ln this manner the tooth is firmly fixed to the back plate el in such a manner that it is possible to finish the tooth accurately to the shape required. After this work has been completed the original wedge 8 is drawn out again, the tooth removed `from the back plate. 4 and the latter provided with a cover plate 9 (Figs. 6 and T), which closes the opening T. Into the opening 7, which is now closed at the back. a wedge il provided with a bottom plate l0 at right angles to it is inserted, so that the bottom plate fills the opening 7. The wedge 11, together with the bottom plate 10, can be fixed by soldering to the anchor or into the opening 7. lt is, however, not necessary to ix it in this manner. On the tooth being placed in position, the hook 6 snaps into the undercut part 3 of the tooth and the two parts cannot come apart through the action of chewing, even without being soldered, as the pressure due to chewing is taken up entirely by the anchor 5, 6, which is clamped in position and is forced against the top of the transverse groove 2.

Fig. 8 shows how, after all the parts have been finished and after the angle shaped wedge has been bent into its shape and soldered to the back plate and the strengthening plate, the metal tooth support thus formed is fitted with the tooth crown, by the crown and the support being pressed together by being pivoted about their upper ends.l The iesilient rear end of the hooked anchor at first bends backwards and forwards while being inserted and at the last moment of uniting the parts the end of the hook snaps into the undercut part of the crown with an audible click. After it has once snapped in, it cannot be removed again, as there is no possibility of causing the end of the hook to spring back again in the hollow space behind it. l

lin the second constructional example sho-wn in Figs. 9 to 11 the hooked anchoring means 22 is inserted in the back plate 21 in a similar manner, as described in detail with reference to the first example, and the stem supported by a wedge-shaped support 23. A vertical support 24 is bent out from the surface of the back plate 21, so that it acts as a supporting rib in the form of a bracketfor the part 23 and the stem of the hooked anchoring part resting thereon. The artificial tooth itself, which is made of porcelain or other suitable material, has in the side 25 facing the back plate a recess 26, which is undercut in the shape of a hook, and below this recess and centrally of it a vertical recess 27. On the two parts being united, as will be readily understood from the detailed description given with reference to the first constructional form, the hook-shaped anchoring member 22 with the supporting part 23 penetrates into the recess 26 and the vertical bracket 24 penetrates into the corresponding vertical recess 27.

According to the form illustrated in Figs. 12 to 15 inclusive, the anchoring member 3() secured to the plate 2S is supported by a f bracket which is provided with a vertical portion 34 that enters the vertical recess shown in the tooth illustrated in Fig. 15. The horizontal portion 33 of the bracket underlies the stem of the anchoring member while the short vertical portion 32 covers the end of said member and the portion 31 lies above the stem 30, as clearly shown in Fig. 14. The hook portion 29 of the anchoring member engages the hook shaped recess shown in dotted lines in the tooth illustrated in Fig. 15.

As certain teeth with the denture are narrow relative to their length, it is preferable to make the connecting device between tooth and back plate vertical instead of horizontal, as is shown by way of example in the constructional form according to Figs. 16 to 19. In this form the back plate 35 is provided with an angle-shaped anchoring means 36, which is placed vertically in its longitudinal direction and consists of the part 36 at right angles to the plate and the hooked part 37 at right angles to the part 3G. Over the part 36 a hook-shaped stiffening piece 38 of sheet metal is suspended as shown in Fig. 1S. Fig. 19 shows the back view of the recess in the corresponding artificial tooth 40. The width of the vertical opening for the angle-shaped anchoring means at Q21 is that of the part 36 plus the part 38 and still greater at its upper end l2 by the thickness of t-he bent-over top end 39 of the part 38. Behind the opening` the undercutting of the tooth is carried through to the full width up to the dotted line 43, so that the bottom of the recess corresponds to the. full width of the bent-over hooked part 37. In this constructional form as well the parts snap together just as in the first example described above in detail.

in all the above examples the various metal parts, after being put together to form the finished support for the artificial tooth, may be soldered or fused together or simply clamped together, for instance, by the parts being squeezed together by means of suitable pliers or by nioking them with small chisels or centre punches, which of itself will make a sufliciently ,firm connection between the metal parts, all the more so after the inser tion of the hooked. anchoring means thus formed into the undercut part of the tooth, the union of the parts thus effected makes it impossible for them to come apart again or even for one part to become displaced relatively to another.

The snap connection between the artificial tooth and its support described in detail in connection with the various above examples is not restricted to the use of metal back plates and metal hooks anchoring means, but may be applied to the fixing of artificial teeth to supports of hard rubber or a similar material. ln the latter case for narrow teeth with vertical hooked anchoring means it is preferably slightly to widen the upper supporting surface, as is shown by the dotted additional pointed parts 441. in Figure 19, in order to allow for the relatively small capacity of caoutchouc for withstanding stresses caused by the act of chewing.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is l. An artificial tooth, comprising, in combination, a tooth having a hook-shaped undercut recess and a narrow slot in communication therewith, a back plate having a hooked anchoring member extending into said recess and engaging the hook-shaped portion thereof, said anchoring member having a resilient stem portion adapted to be temporarily deformed to permit the hook of the anchoring member to be introduced into said recess through said slot, and wedging means for securing the anchoring member in said slot with its hook portion in engagement with the hook shaped portion of the recess, said wedging means forming a reinforcement for said stem for a port-ion of its length adjacent to the back plate. ,y

2. An artificial tooth, comprising, in combination, a tooth having a hook-shaped undercut recess and a narrow slot in com munication therewith, a back plate having a portion punched out therefrom and forming a hook-shaped anchoring member ex;- tending into said recess and engaging the hook-shaped portion thereof, said anchoring member having a resilient stem portion adapted to be temporarily deformed to permit the hook thereof to be introduced into said recess through said slot, and a reinforcing member having two portions one at an angle to the other, one portion extending in parallelism with the anchoring member and adapted to retain the hook-portion thereof in engagement with the hook portion of the recess and the other portion of said reinforcing member secured to said plate.

3. An artificial tooth, comprising, in combination, a tooth having a hook-shaped undercut recess and a narrow slot in communication therewith, a back plate having a portion punched out therefrom and forming a hook-shaped anchoring member extending into said recess and engaging the l'iook-shaped portion thereof` said anchoring member having a resilient stem portion adapted to be temporarily deformed to permit the hooi; thereof to be introduced into said recess through said slot, and a reinforcing member having two portions one at an angle to the other, one portion extending in parallelism with the anchoring member and adapted to retain the hook-portion thereof in engagement with the hook portion of the recess and the other portion of said reinforcing member secured within the punched out opening in the plate.

el. An artificial tooth, comprising, in coinbination, a tooth having a hook-shaped undercut recess and a narrow slot in communication therewith, a back plate having a portion punched out therefrom and forming a hook-shaped anchoring member extending into said recess and engaging the hookshaped portion thereof, said anchoring me1nber having a resilient stem portion adapted to be temporarily deformed to permit the hook thereof to be introduced into said recess through said slot, and a reinforcing member having two portions one at an angle to the other, one portion extending in parallelism with the anchoring meniber and adapted to retain the hook-portion thereof in engagement with the hook portion of the recess the other portion of said reinforcing member secured within the punched out opening in the plate, and a plate secured to said back plate in position to cover the punched out portion thereof.

In testimony whereof I affix my signature in presence of two witnesses.

Dn. HANS STURM. IVitnesses FRANK BnsNoK, ZAMUEL LANUEG.

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